The present technology relates to implantable compositions that exhibit desired release profiles of bioactive agents.
Various approaches have been employed in attempting to provide implantable compositions that provide systemic or local delivery of drug actives. Some active technologies, e.g., insulin pumps, have been developed to provide variable rate drug delivery. However, these require specialized equipment and are desirable for use in only chronic conditions. Alternatively, passive drug releasing implants have been developed to provide a post-implantation burst or spike of the active agent after in vivo biodegradation of a long-term coating. Many such approaches simply provide long-term release at a constant rate. However, among other issues, these materials can exhibit premature release of the bioactive agent through the layer of long-term biodegradable coating. Therefore, it would be advantageous to provide implants capable of releasing bioactive agents in a manner that is more selective, with decreased risk of premature release, and that is adaptable to provide any of various pre-selected drug release profiles.